Electromigration testing of integrated circuit interconnections

The electromigration phenomenon has been one of the most intriguing physical problems in the semiconductor device reliability. The models to explain the phenomenon are here revised, together with the influence of materials and their microstructure. The various measuring techniques are described, including the design of special test patterns, and statistical data analysis is briefly reviewed.     

Turbulence modelling of the shear layers in the trailing edge region of a modern rear-loaded airfoil at incidence

After carefull analysis in a turbulent zero-pressure gradient flow, various simple algebraic turbulence models were applied to the almost separated flow on the upperside of an airfoil at incidence. The Johnson-King and Horton non-equilibrium (or rate equation) models give clearly improved results.     

The core of discontinuous games

The traditional design of cooperative games implicitly assumes that preferences are continuous. However, if agents implement tie breaking procedures, preferences are effectively lexicographic and thus discontinuous. This rouses concern over whether classic core nonemptiness theorems apply in such settings. We show that balanced NTU games may have empty cores when agents have discontinuous preferences. Moreover, exchange economies may lack coalitionally rational trades when consumers implement tie breaking rules, even if these rules are themselves continuous and convex as are all first order preferences. Results are more positive when “utility” is transferable. We prove that balancedness is necessary and sufficient to ensure a nonempty core in lexicographic TU games.     

Incomplete inversion and double-valued fundamental linewidth ofinfrared HeNe and HeXe lasers

We have measured the quantum-limited linewidths of small HeNe 3.39 μm and HeXe 3.51 μm lasers. In contrast to the expected Schawlow-Townes behaviour strong deviations from the inverse power dependence are observed, leading to a double-valued relation between the linewidth and the output power. This phenomenon is analyzed in terms of the increase of spontaneous emission, by a factor N_sp, due to incompleteness of the inversion. Our analysis shows that typically N_sp has a value ranging from 1-10. Combining existing models for the pump power dependence of the level populations with measurements of the small signal gain, we are able to explain the observed double-valued linewidth behaviour in a quantitative way     

Mine operating accurate stability control with optical fibersensing and Bragg grating technology: the European BRITE/EURAM STABILOSproject

Recent developments of stability control in mines, essentially based on Ge-doped fiber Bragg gratings (FBG) are reported including results about the different aspects of the system: accurate characterizations of FBG, sensor network topology and multiplexing method, user interface design and sensor packaging     

Theory for passive mode-locking in semiconductor laser structuresincluding the effects of self-phase modulation, dispersion, and pulsecollisions

We present a theory for passive mode-locking in semiconductor laser structures using a semiconductor laser amplifier and absorber. The mode-locking system is described in terms of the different elements in the semiconductor laser structure. We derive mode-locking conditions and show how other mode-locking parameters, like pulse width and pulse energy, are determined by the mode-locking system. System parameters, like bandwidth, dispersion, and self-phase modulation are shown to play an important role in mode-locking conditions and results. We also discuss the effects of pulse collisions and positions of the mode-locking elements inside the cavity on mode-locking stability and show that these effects can be easily included in the presented model. Finally, we give a number of design rules and recommendations for fabricating passively mode-locked lasers     

Phase-insensitive all-optical transistors based on second-ordernonlinearities

We demonstrate and compare two phase-insensitive all-optical transistors (AOT's) based on frequency-degenerate quadratic three-wave interactions. In particular, we demonstrate gain using KTP in a type II geometry. Both AOT's exploit the phase insensitivity inherent to three-wave parametric processes when only two fields are input, providing amplification of a small signal at the operating frequency via the interaction with a second-harmonic wave. The first scheme is based on successive up- and down-conversion (i.e., cascading) while the second relies on parametric down-conversion. We obtain gains of 5 and 160 in the two configurations, respectively, with a significant background and output coherent to the pump in the first case, no background and coherence between output and signal in the second     

Lifetime study of high-spin states in 104,105In

In the neutron deficient isotopes _104,105In lifetimes of high spin states in the range from 0.5 ps to 600 ps have been measured in a coincidence recoil distance Doppler shift (RDDS) experiment. By combining the Doppler shift attenuation (DSA) and RDDS methods at few μm flight distances, the problem of delayed feeding has been avoided and very short lifetimes in the range 0.5–0.8 ps have been determined. Shell model calculations with strong restrictions for the neutron orbitals reveal good agreement with experimental level energies and still fair agreement for most measured B(M1) and B(E2) values. Received: 30 June 1998